The only change i made is add math.floor on the x and y calculations, because the calendar worked in English but didn't work in Spanish and other language i download. What the sense of that? i don't know...
And make dayCount = dayCount + 1, to create a space between 1 and 31 (because is annoying to see the two days together, but that was my fault).

The problem is caused by the bitmap numbers which have additional padding on the sides. This makes the day area larger than what is covered by the numbers. I think I'll have to add new attributes for the single day area.